如何计算字体大小？
问题描述：
我有一个复杂的js函数与一个方程，其中我实际上需要了解以像素字体大小占用多少空间。
I have a complex js function with an equation in which I actually need to understand how much space in pixels font sizes take up.
我注意到一些字体
如何计算字体大小？如果它设置为 12px ，在css中， 12px 是什么意思？是 12px 宽吗？高？或者是对角像素测量？
How is a font's size calculated? If its set to 12px, in css, what does the 12px mean? Is that 12px wide? High? Or is it a diagonal pixel measurement?
答
请参阅 spec ：
字体大小对应于em
方块，这是在排版中使用的概念。
请注意，某些字形可能会在其正方形之外出现
。
The font size corresponds to the em square, a concept used in typography.
Note that certain glyphs may bleed outside their em squares.